Grain Refinement and Strengthening of an Aluminum Alloy Subjected to Severe Plastic Deformation through Equal-Channel Angular Pressing

In the present study, the microstructure, mechanical properties, and stored energy of an aluminum alloy containing iron-rich fine precipitates, subjected to severe plastic deformation through equal-channel angular pressing (ECAP), were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Up to four passes through ECAP resulted in significant nanometer-scale grain refinement, as well as the accumulation of lattice defects, such as dislocations and mesoscopic shear planes. This resulted in a noticeable enhancement in the Vickers microhardness and the flow stress after ECAP. Differential scanning calorimetry results showed that the ECAP’ed material exhibited two exothermal peaks at 222 ± 2 °C and 362 ± 2 °C, with total thermal effects of ΔH = 4.35 and 6.5 J/g, respectively. Slight increases in the ECAP’ed material microhardness and flow stress were observed at 200 °C. The heat release, at a relatively low temperature, and the slight improvement in the mechanical properties were attributed to the evolution of low- and high-angle misorientation, with the strain and the pinning of tangled dislocation caused by the existing fine particles. The second peak was attributed to grain growth, resulting in a significant softening of the material

Chemistry journals and research trends in Arab countries: A bibliometric analysis

Arab countries have been working hard to establish centers of research excellence and industrial clusters, especially in chemistry, based on the best technologies and practices. It is of utmost importance for decision-makers and academics to estimate the extent of chemistry research progress in Arab countries which differ substantially in economic development and graduate and postgraduate education. This study aims to highlight the current chemistry research trends and analyze chemistry journals in Arab countries. The citation rates, H-Index, SJR (Scimago Journal and Country Rank), and co-occurrence of keywords and authorship were compared between chemistry journals that are published by Arab countries and those published by the rest of the world between 1996 and 2022, referring to SJR report. Saudi Arabia and Egypt are the Arab countries with the largest citations number, published documents, and SJR indicators. Despite Arab countries' efforts to promote scientific research and build industrial clusters, the comparison of Arab countries to the rest of the world revealed that the Arab countries' SJR, H-index, citations per document in the previous two years, and total citations in the last three years are statistically significantly lower than those of the rest of the world. Many topics, such as nanoparticles, graphene, drug delivery, and molecular docking, are addressed by Arab countries as well as by the rest of the world. Arab countries, on the other hand, are more interested in nanoparticles than the rest of the world, which is more interested in catalysis. To strengthen their impact on the chemistry research field, Arab countries should intensify their collaboration with the rest of the world and focus on more centered topics